An optical pickup device irradiates a recording plane of an optical disk with a recording/reproduction laser beam, to thus record or reproduce information. At this time, in order to effect recording and reproduction with high accuracy, there is a necessity for holding an objective lens for gathering the recording/reproduction laser beam on an optical disk in parallel with the optical disk. To this end, an objective lens is mounted with high accuracy in a production stage. For instance, Japanese Patent Publication Laid-Open No. 2000-57585 describes an objective lens tilt-monitoring device capable of adjusting the tilt of mount of the objective lens with high accuracy. This device irradiates the periphery of the objective lens with light, and detects the inclination of the objective lens in accordance with the intensity of light reflected from the periphery and a position where reflected light has returned. This device enables high-precision mounting of the objective lens.
However, even when the objective lens is mounted with high accuracy, there may arise a case where an objective lens does not lie parallel to an optical disk, because of warpage in an optical disk. Accordingly, a recorded area of the optical disk is subjected to test exposure while the tilt angle of the objective lens is being changed. The tilt angle of the objective lens achieved when reproduction quality of reference value or more is achieved and stored as reference tilt angle. There is adopted tilt correction for correcting the tilt angle of an objective lens by reference to the stored reference tilt angle. Even when warpage has arisen in an optical disk, the objective lens and the optical disk can be held in parallel with each other, thereby enhancing reliability of recording and reproduction of information.
However, the reference tilt angle has hitherto been stored as a voltage applied to a drive device which tilts and drives an objective lens. The drive device comprises two electromagnetic coils which impart vertical thrust to respective right and left objective lenses. When the objective lens shifts in a radial direction as a result of the optical pickup device having performed seeking operation in the radial direction of a disk, a displacement arises between the center of the thrust originating from an electromagnetic coil and the centroid of a lens holder assembly, and the tilt angle varies even for a constant voltage. In short, no correspondence exists between an applied voltage and a tilt angle. Accordingly, even when a storage voltage has been applied, there is a problem of the objective lens failing to assume a reference tilt angle and a drop arising in recording/reproduction accuracy.
Therefore, the present invention aims at providing an optical pickup device which enables a further improvement in recording/reproduction accuracy.